Good evening. While some of you may be reading this with thunder booming around outside lets have a look at the legacy that follows over the next 10-14 days as I look at the 12 midday outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Saturday July 27th 2013.The General Situation. The UK lies in the path of a thundery plume moving NNE over Central and SE parts of the UK in the next 6 hours. Following on behind will be much less humid and fresher SW winds with sunshine and showers lasting through Sunday and Monday. Towards midweek Low pressure moves North to the west of the UK with an attached trough carrying rain Northwards followed by a return to warm and humid conditions again later in the week. A further thundery breakdown looks possible yet again late in the week and before the weekend as a further thundery disturbance makes it's way up from France and Spain.
GFS then brings Low pressure across from the West painfully slowly next weekend with a mix of sunshine and showers, some heavy. It also finally releases the SE of the close proximity to hot air on the Continent with cooler West and eventually NW winds blowing down over the UK. These strengthen later in the run and it will feel quite cool in the strength of the wind with showers frequent and possibly heavy in the North and West. The run ends with lighter winds but still a showery theme with a new Low pressure out to the West coming in at the end of the run.
The GFS Ensembles indicate a mostly Westerly based pattern once the final warm plume in this period wafts up across the South and East later in the week. The most rainfall will always be biased towards the North but even the SE will see some at times in temperatures eventually settling close to average.
The Jet Stream shows the flow undulating across the Atlantic and across the UK either from the SW or West over the coming few weeks.
UKMO tonight shows slack pressure over the UK late in the week with slow moving showers across the north and West while the South and East sees a lot of dry weather between more scattered showers. It could still be very warm in the SE for a time but the chance of thundery rain moving up from the South at times remain.
GEM tonight is much more bullish about a substantial plume later in the week taking High pressure up to Scandinavia encapsulating much of NW Europe with very warm and sunny weather. However, as usual the UK will lie on the edge of this feature with Low pressure edging in from the South or west at times gradually bringing in the risk of showers and thunderstorms later.
NAVGEM maintains warm or very warm weather at the end of the run in the SE with the risk of showers and thunderstorms as a trough crosses East late in the week.
ECM makes much less of this weeks warmer phase than previous runs with thundery rain crossing East on Friday. By Saturday a small High pressure area forms over the South with a fine and quite sunny start to the weekend in the South while the North sees a few more showers and a cooler NW wind. Late in the run in what appears a strange and complex evolution thundery rain spreads North again and brings a change to cooler and more showery weather again to end the run.
In Summary there is a complex structure of output tonight which show the same basic patterns. They can be split into the two weeks with week 1 offering changeable conditions over the UK with conditions that will range from hot and sunny and cooler and wet with some thunderstorms in the SE at times to week 2 which seems to be biased towards a general cooling set up with rain at times on Atlantic Westerlies and temperatures close to average.
Originally Posted by: GIBBY